Objective: To evaluate the interobserver and intraobserver agreement of parameters of optic nerve head by Heidelberg Retina Tomograph (HRT).
Methods: Optic nerve heads from 50 eyes (30 subjects) were imaged with the HRT. Three ophthalmologists majoring in glaucoma traced the disc margin with a contour line. One of these observers, repeatedly traced the disc margin with contour line in triplicate at three different times. Eleven topographic parameters of optic nerve head (including disc area, cup area, cup/disc area ratio, rim area, cup volume, rim volume, mean cup depth, maximum cup depth, cup shape measure, mean retinal nerve fiber layer thickness, sectional area of retinal nerve fiber layer) were analyzed with HRT software (version 2.01). Intraclass coefficients (ICC) and agreement of result estimation (kappa value) were calculated.
Results: The ICCs results among three observers on 12 parameters of optic nerve head topography were 0.976 - 0.999, which showed almost perfect agreement; and the kappa value were 0.649 approximately 0.767, which showed substantial agreement. The ICC of the same observer in different times were 0.983 approximately 0.999, which showed almost perfect agreement; and the Kappa values were 0.810 approximately 0.951, which showed substantial agreement.
Conclusions: Tracing the optic nerve head with contour line on HRT image is substantial to almost perfect within both interobserver and intraobserver in experienced ophthalmologist. This procedure is suitable for clinical diagnosis and follow-up observation of glaucoma.